Multi-core microprocessor power gating cache restoral mechanism

ABSTRACT

An apparatus includes a fuse array and a stores. The fuse array is disposed on a die, and is programmed with compressed configuration data for a plurality of cores. The stores is coupled to the plurality of cores, and includes a plurality of sub-stores that each correspond to each of the plurality of cores, where one of the plurality of cores accesses the semiconductor fuse array upon power-up/reset to read and decompresses the compressed configuration data, and stores a plurality of decompressed configuration data sets for one or more cache memories within the each of the plurality of cores in the plurality of sub-stores, and where, following a power gating event, one of the each of the plurality of cores subsequently accesses a corresponding one of the each of the plurality of sub-stores to retrieve and employ the decompressed configuration data sets to initialize the caches.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to the following co-pending U.S. patentapplications, each of which has a common assignee and common inventors.

SER. FILING NO. DATE TITLE 13/972,297 Aug. 21, 2013 APPARATUS AND METHODFOR STORAGE AND (CNTR.2617) DECOMPRESSION OF CONFIGURATION DATA13/972,358 Aug. 21, 2013 MULTI-CORE FUSE DECOMPRESSION MECHANISM(CNTR.2672) 13/972,414 Aug. 21, 2013 EXTENDED FUSE REPROGRAMMABILITY(CNTR.2673 MECHANISM 13/972,481 Aug. 21, 2013 APPARATUS AND METHOD FOREXTENDED CACHE (CNTR.2674) CORRECTION 13/972,657 Aug. 21, 2013CORE-SPECIFIC FUSE MECHANISM FOR A MULTI- (CNTR.2675) CORE DIE13/972,609 Aug. 21, 2013 APPARATUS AND METHOD FOR CONFIGURABLE(CNTR.2686) REDUNDANT FUSE BANKS 13/972,690 Aug. 21, 2013 APPARATUS ANDMETHOD FOR RAPID FUSE BANK (CNTR.2687) ACCESS IN A MULTI-CORE PROCESSOR13/972,725 Aug. 21, 2013 MULTI-CORE MICROPROCESSOR CONFIGURATION(CNTR.2697) DATA COMPRESSION AND DECOMPRESSION SYSTEM 13/972,741 Aug.21, 2013 APPARATUS AND METHOD FOR (CNTR.2698) COMPRESSION OFCONFIGURATION DATA 13/972,768 Aug. 21, 2013 MICROPROCESSOR MECHANISM FOR(CNTR.2699) DECOMPRESSION OF FUSE CORRECTION DATA 13/972,785 Aug. 21,2013 MICROPROCESSOR MECHANISM FOR (CNTR.2700) DECOMPRESSION OF CACHECORRECTION DATA 13/972,794 Aug. 21, 2013 APPARATUS AND METHOD FORCOMPRESSION (CNTR.2705) AND DECOMPRESSION OF MICROPROCESSORCONFIGURATION DATA 13/972,812 Aug. 21, 2013 CORRECTABLE CONFIGURATIONDATA (CNTR.2706) COMPRESSION AND DECOMPRESSION SYSTEM        —MULTI-CORE APPARATUS AND METHOD FOR (CNTR.2732) RESTORING DATA ARRAYSFOLLOWING A POWER GATING EVENT        — MULTI-CORE DATA ARRAY POWERGATING (CNTR.2776) RESTORAL MECHANISM        — APPARATUS AND METHOD FORREPAIRING CACHE (CNTR.2778 ARRAYS IN A MULTI-CORE MICROPROCESSOR

BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates in general to the field of microelectronics, andmore particularly to apparatus and methods for restoring compressedcache repair data following a multi-core power gating event.

Description of the Related Art

Integrated device technologies have exponentially advanced over the past40 years. More specifically directed to the microprocessor fields,starting with 4-bit, single instruction, 10-micrometer devices, theadvances in semiconductor fabrication technologies have enableddesigners to provide increasingly more complex devices in terms ofarchitecture and density. In the 80's and 90's, so-called pipelinemicroprocessors and superscalar microprocessors were developedcomprising millions of transistors on a single die. And now 20 yearslater, 64-bit, 32-nanometer devices are being produced that havebillions of transistors on a single die, and which comprise multiplemicroprocessor cores for the processing of data.

One requirement that has persisted since these early microprocessorswere produced is the need to initialize these devices with configurationdata when they are powered up or when they are reset. For example, manyarchitectures enable devices to be configured to execute at one of manyselectable frequencies and/or voltages. Other architectures require thateach device have a serial number and other information that can be readvia execution of an instruction. Yet other devices requireinitialization data for internal registers and control circuits. Stillother microprocessors, particularly that with on-board cache memories,utilize repair data to implement redundant circuits within thesememories to correct for fabrication errors.

As one skilled in the art will appreciate, designers have traditionallyemployed semiconductor fuse arrays on-die to store and provide initialconfiguration and repair data. These fuse arrays are generallyprogrammed by blowing selected fuses therein after a part has beenfabricated, and the arrays contain thousands of bits of informationwhich are read by a corresponding device upon power-up/reset toinitialize and configure the device for operation.

As device complexity has increased over the past years, the amount ofconfiguration/repair data that is required for a typical device hasproportionately increased. Yet, as one skilled in the art willappreciate, though transistor size shrinks in proportion to thesemiconductor fabrication process employed, semiconductor fuse sizeincreases due to the unique requirements for programming fuses on die.This phenomenon, in and of itself, is a problem for designers, who areprevalently constrained by real estate and power considerations. Inother words, there is just not enough real estate on a given die tofabricate a huge fuse array.

In addition, the ability to fabricate multiple device cores on a singledie has geometrically exacerbated the problem, because configurationrequirements for each of the cores result in a requirement for a numberof fuses on die, in a single array or distinct arrays, that isproportional to the number of cores disposed thereon.

Furthermore, as one skilled in the art will appreciate, multiple-coredevices utilize complex power-saving modes of operation that result inone or more of the cores being powered down in a so-called power gatingevent (or, “sleep mode”) when not in use. Consequently, when a core ispowered up following a power gating event, the same requirement forinitialization, configuration, and repair persists, except thatinitialization speed requirements are much more stringent.

Therefore, what is needed is apparatus and methods that enableconfiguration/repair data to be stored and provided to a multi-coredevice that require significantly less real estate and power on a singledie than that which has heretofore been provided.

In addition, what is needed is a fuse array mechanism that can store andprovide significantly more configuration/repair data than currenttechniques while requiring the same or less real estate on a multi-coredie.

Furthermore, what is needed is a technique that facilitates promptinitialization, configuration, and repair of a multi-core devicefollowing a power gating event.

SUMMARY OF THE INVENTION

The present invention provides a superior technique for restoringconfiguration data following a power gating event. In one aspect, anapparatus for providing configuration data to an integrated circuit isconsidered. The apparatus includes a semiconductor fuse array and astores. The semiconductor fuse array is disposed on a die, and isprogrammed with compressed configuration data for a plurality of coresdisposed on the die, and coupled to the semiconductor fuse array. Thestores is coupled to the plurality of cores, and includes a plurality ofsub-stores that each correspond to each of the plurality of cores, whereone of the plurality of cores is configured to access the semiconductorfuse array upon power-up/reset to read and decompress the compressedconfiguration data, and to store a plurality of decompressedconfiguration data sets for one or more cache memories within the eachof the plurality of cores in the plurality of sub-stores, and where,following a power gating event, one of the each of the plurality ofcores subsequently accesses a corresponding one of the each of theplurality of sub-stores to retrieve and employ the decompressedconfiguration data sets to initialize the one or more caches.

One aspect of the present invention contemplates an apparatus forproviding configuration data to an integrated circuit device. Theapparatus includes a multi-core microprocessor. The multi-coremicroprocessor has a semiconductor fuse array and a stores. Thesemiconductor fuse array is disposed on a die, and is programmed withcompressed configuration data for a plurality of cores disposed on thedie, and coupled to the semiconductor fuse array. The stores is coupledto the plurality of cores, and includes a plurality of sub-stores thateach correspond to each of the plurality of cores, where one of theplurality of cores is configured to access the semiconductor fuse arrayupon power-up/reset to read and decompress the compressed configurationdata, and to store a plurality of decompressed configuration data setsfor one or more cache memories within the each of the plurality of coresin the plurality of sub-stores, and where, following a power gatingevent, one of the each of the plurality of cores subsequently accesses acorresponding one of the each of the plurality of sub-stores to retrieveand employ the decompressed configuration data sets to initialize theone or more caches.

Another aspect of the present invention comprehends a method forconfiguring an integrated circuit. The method includes first disposing asemiconductor fuse array on a die, into which is programmed compressedconfiguration data for a plurality of cores disposed on the die, andcoupled to the semiconductor fuse array; and second disposing a storeson the die, the stores comprising a plurality of sub-stores that eachcorrespond to each of the plurality of cores, where one of the pluralityof cores is configured to access the semiconductor fuse array uponpower-up/reset to read and decompress the compressed configuration data,and to store a plurality of decompressed configuration data sets for oneor more cache memories within the each of the plurality of cores in theplurality of sub-stores, and where, following a power gating event, oneof the each of the plurality of cores subsequently accesses acorresponding one of the each of the plurality of sub-stores to retrieveand employ the decompressed configuration data sets to initialize theone or more caches.

Regarding industrial applicability, the present invention is implementedwithin a MICROPROCESSOR which may be used in a general purpose orspecial purpose computing device.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features, and advantages of the presentinvention will become better understood with regard to the followingdescription, and accompanying drawings where:

FIG. 1 is a block diagram illustrating a present day microprocessor corethat includes a fuse array for providing configuration data to themicroprocessor core;

FIG. 2 is a block diagram depicting a fuse array within themicroprocessor core of FIG. 1 which includes redundant fuse banks thatmay be blown subsequent to blowing first fuse banks within the fusearray;

FIG. 3 is a block diagram featuring a system according to the presentinvention that provides for compression and decompression ofconfiguration data for a multi-core device;

FIG. 4 is a block diagram showing a fuse decompression mechanismaccording to the present invention;

FIG. 5 is a block diagram illustrating an exemplary format forcompressed configuration data according to the present invention;

FIG. 6 is a block diagram illustrating an exemplary format fordecompressed microcode patch configuration data according to the presentinvention;

FIG. 7 is a block diagram depicting an exemplary format for decompressedmicrocode register configuration data according to the presentinvention;

FIG. 8 is a block diagram featuring an exemplary format for decompressedcache correction data according to the present invention;

FIG. 9 is a block diagram showing an exemplary format for decompressedfuse correction data according to the present invention; and

FIG. 10 is a block diagram showing an alternative exemplary format fordecompressed fuse correction data according to the present invention;and

FIG. 11 is a block diagram illustrating an multi-core apparatusaccording to the present invention that provides for prompt restoral ofcache repair data following a power gating event.

DETAILED DESCRIPTION

Exemplary and illustrative embodiments of the invention are describedbelow. In the interest of clarity, not all features of an actualimplementation are described in this specification, for those skilled inthe art will appreciate that in the development of any such actualembodiment, numerous implementation specific decisions are made toachieve specific goals, such as compliance with system-related andbusiness related constraints, which vary from one implementation to thenext. In addition, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure. Various modifications to the preferred embodiment willbe apparent to those skilled in the art, and the general principlesdefined herein may be applied to other embodiments. Therefore, thepresent invention is not intended to be limited to the particularembodiments shown and described herein, but is to be accorded the widestscope consistent with the principles and novel features hereindisclosed.

The present invention will now be described with reference to theattached figures. Various structures, systems, and devices areschematically depicted in the drawings for purposes of explanation onlyand so as to not obscure the present invention with details that arewell known to those skilled in the art. Nevertheless, the attacheddrawings are included to describe and explain illustrative examples ofthe present invention. The words and phrases used herein should beunderstood and interpreted to have a meaning consistent with theunderstanding of those words and phrases by those skilled in therelevant art. No special definition of a term or phrase (i.e., adefinition that is different from the ordinary and customary meaning asunderstood by those skilled in the art) is intended to be implied byconsistent usage of the term or phrase herein. To the extent that a termor phrase is intended to have a special meaning (i.e., a meaning otherthan that understood by skilled artisans) such a special definition willbe expressly set forth in the specification in a definitional mannerthat directly and unequivocally provides the special definition for theterm or phrase.

In view of the above background discussion on device fuse arrays andassociated techniques employed within present day integrated circuitsfor providing configuration data during initial power-up, a discussionof the limitations and disadvantages of those techniques will bepresented with reference to FIGS. 1-2. Following this, a discussion ofthe present invention will be presented with reference to FIGS. 3-10.The present invention overcomes all of the limitations and disadvantagesdiscussed below by providing apparatus and methods for employingcompressed configuration in a multi-core die which utilize less powerand real estate on the multi-core die, which provide for expeditiousrestoral of configuration and repair data following power gating events,and which are more reliable than that which has heretofore beenprovided.

DEFINITIONS

Integrated Circuit (IC): A set of electronic circuits fabricated on asmall piece of semiconductor material, typically silicon. An IC is alsoreferred to as a chip, a microchip, or a die.

Central Processing Unit (CPU): The electronic circuits (i.e.,“hardware”) that execute the instructions of a computer program (alsoknown as a “computer application,” “application program,” “program,” or“application”) by performing operations on data that include arithmeticoperations, logical operations, and input/output operations.

Microprocessor: An electronic device that functions as a CPU on a singleintegrated circuit. A microprocessor receives digital data as input,processes the data according to instructions fetched from a memory(either on-die or off-die), and generates results of operationsprescribed by the instructions as output. A general purposemicroprocessor may be employed in devices including, but not limited to,a desktop, mobile, or tablet computer, and may be utilized for taskssuch as, but not limited to, computation, text editing, multimediadisplay, and Internet browsing. A microprocessor may also be disposed inan embedded system to control a wide variety of devices that includeappliances, mobile telephones, smart phones, and industrial controldevices.

Multi-Core Processor: Also known as a multi-core microprocessor, amulti-core processor is a microprocessor having multiple CPUs (alsoknown as “cores”) fabricated on a single integrated circuit.

Instruction Set Architecture (ISA) or Instruction Set: A part of acomputer architecture related to programming that includes data types,instructions, registers, addressing modes, memory architecture,interrupt and exception handling, and input/output. An ISA includes aspecification of the set of opcodes (i.e., machine languageinstructions), and the native commands implemented by a particular CPU.

x86-Compatible Microprocessor: A microprocessor capable of executingcomputer applications that are programmed according to the x86 ISA.

Microcode: A term employed to refer to a plurality of microinstructions. A micro instruction (also referred to as a “nativeinstruction”) is an instruction at the level that a microprocessorsub-unit executes. Exemplary sub-units include integer units, floatingpoint units, MMX units, and load/store units. For example, microinstructions are directly executed by a reduced instruction set computer(RISC) microprocessor. For a complex instruction set computer (CISC)microprocessor such as an x86-compatible microprocessor, x86instructions are translated into associated micro instructions, and theassociated micro instructions are directly executed by a sub-unit orsub-units within the CISC microprocessor.

Fuse: A conductive structure typically arranged as a filament which canbe broken at select locations by applying a voltage across the filamentand/or current through the filament. Fuses may be deposited at specifiedareas across a die topography using well known fabrication techniques toproduce filaments at all potential programmable areas. A fuse structureis blown (or unblown) subsequent to fabrication to provide for desiredprogrammability of a corresponding device disposed on the die.

Turning to FIG. 1, a block diagram 100 is presented illustrating apresent day microprocessor core 101 that includes a fuse array 102 forproviding configuration data to the microprocessor core 101. The fusearray 102 comprises a plurality of semiconductor fuses (not shown)typically arranged in groups known as banks. The fuse array 102 iscoupled to reset logic 103 that includes both reset circuits 104 andreset microcode 105. The reset logic 103 is coupled to control circuits107, microcode registers 108, microcode patches elements 109, and cachecorrection elements 110. An external reset signal RESET is coupled tothe microprocessor core 101 and is routed to the reset logic 103.

As one skilled in the art will appreciate, fuses (also called “links” or“fuse structures”) are employed in a vast number of present dayintegrated circuit devices to provide for configuration of the devicesafter the devices have been fabricated. For example, consider that themicroprocessor core 101 of FIG. 1 is fabricated to provide functionalityselectively either as a desktop device or a mobile device. Accordingly,following fabrication, prescribed fuses within the fuse array 102 may beblown to configure the device as, say, a mobile device. Accordingly,upon assertion of RESET, the reset logic 103 reads the state of theprescribed fuses in the fuse array 102 and the reset circuits 104(rather than reset microcode 105, in this example) enable correspondingcontrol circuits 107 that deactivate elements of the core 101exclusively associated with desktop operations and activate elements ofthe core 101 exclusively associated with mobile operations.Consequently, the core 101 is configured upon power-up reset as a mobiledevice. In addition, the reset logic 103 reads the state of the otherfuses in the fuse array 102 and the reset circuits 104 (rather thanreset microcode 105, in this example) enable corresponding cachecorrection circuits 107 provide corrective mechanisms for one or morecache memories associated (not shown) with the core 101. Consequently,the core 101 is configured upon power-up reset as a mobile device andcorrective mechanisms for its cache memories are in place.

The above example is merely one of many different uses for configurationfuses in an integrated circuit device such as a microprocessor core 101of FIG. 1. One skilled in the art will appreciate that other uses forconfiguration fuses include, but are not limited to, configuration ofdevice specific data (e.g., serial numbers, unique cryptographic keys,architecture mandated data that can be accessed by users, speedsettings, voltage settings), initialization data, and patch data. Forexample, many present day devices execute microcode and often requireinitialization of registers 108 that are read by the microcode. Suchinitialization data may be provided by microcode register fuses (notshown) within the fuse array 102, which are read upon reset and providedto the microcode registers 108 by the reset logic 103 (using either thereset circuits 104, the reset microcode 105, or both elements 104-105).For purposes of the present application, the reset circuits 104 comprisehardware elements that provide certain types of configuration data,which cannot be provided via the execution of the reset microcode 105.The reset microcode 105 comprises a plurality of micro instructionsdisposed within an internal microcode memory (not shown) that isexecuted upon reset of the core 101 to perform functions correspondingto initialization of the core 101, those functions including provisionof configuration data that is read from the fuse array 102 to elementssuch as microcode registers 108 and microcode patch mechanisms 109. Thecriteria for whether certain types of configuration data provided viafuses can be distributed to the various elements 107-110 in the core 101via reset microcode 105 or not is a function primarily of the specificdesign of the core 101. It is not the intent of the present applicationto provide a comprehensive tutorial on specific configuration techniquesthat are employed to initialize integrated circuit devices, for oneskilled in the art will appreciate that for a present day microprocessorcore 101 the types of configurable elements 107-110 generally fall intofour categories as are exemplified in FIG. 1: control circuits,microcode registers, microcode patch mechanisms, and cache correctionmechanisms. Furthermore, one skilled will appreciate that the specificvalues of the configuration data significantly vary based upon thespecific type of data. For instance, a 64-bit control circuit 107 mayinclude ASCII data that prescribes a serial number for the core 101.Another 64-bit control register may have 64 different speed settings,only one of which is asserted to specify an operating speed for the core101. Microcode registers 108 may typically be initialized to all zeros(i.e. logic low states) or to all ones (i.e., logic high states).Microcode patch mechanisms 109 may include an approximately uniformdistribution of ones and zeros to indicate addresses in a microcode ROM(not shown) along with replacement microcode values for those addresses.Finally, cache correction (i.e., “repair”) mechanisms may comprise verysparse settings of ones to indicate substitution control signals toreplace a certain cache sub-bank element (i.e., a row or a column) witha particular replacement sub-bank element to enable the repair of one ormore cache memories.

Fuse arrays 102 provide an excellent means for configuring a device suchas a microprocessor core 101 subsequent to fabrication of the device. Byblowing selected fuses in the fuse array 102, the core 101 can beconfigured for operation in its intended environment. Yet, as oneskilled in the art will appreciate, operating environments may changefollowing programming of the fuse array 102. Business requirements maydictate that a device 101 originally configured as, say, as desktopdevice 101, be reconfigured as a mobile device 101. Accordingly,designers have provided techniques that utilize redundant banks of fuseswithin the fuse array 102 to provide for “unblowing” selected fusestherein, thus enabling the device 101 to be reconfigured, fabricationerrors to be corrected, and etc. These redundant array techniques willnow be discussed with reference to FIG. 2.

Referring now to FIG. 2, a block diagram 200 is presented depicting afuse array 201 within the microprocessor core 101 of FIG. 1 includingredundant fuse banks 202 RFB1-RFBN that that may be blown subsequent toblowing first fuse banks 202 PFB1-PFBN within the fuse array 201. Eachof the fuse banks 202 PFB1-PFBN, RFB1-RFBN comprises a prescribed numberof individual fuses 203 corresponding to specific design of the core101. For example, the number of fuses 203 in a given fuse bank 202 maybe 64 fuses 203 in a 64-bit microprocessor core 101 to facilitateprovision of configuration data in a format that is easily implementedin the core 101.

The fuse array 201 is coupled to a set of registers 210-211 that aretypically disposed within reset logic in the core 101. A primaryregister PR1 is employed to read one of the first fuse banks PFB1-PFBN(say, PFB3 as is shown in the diagram 200) and a redundant register RR1is employed to read a corresponding one of the redundant fuse banksRFB1-RFBN. The registers 210-211 are coupled to exclusive-OR logic 212that generates an output FB3.

In operation, subsequent to fabrication of the core 101, the first fusebanks PFB1-PFBN are programmed by known techniques with configurationdata for the core 101. The redundant fuse banks RFB1-RFBN are not blownand remain at a logic low state for all fuses therein. Uponpower-up/reset of the core 101, both the first fuse banks PFB1-PFBN andthe redundant fuse banks RFB1-RFBN are read as required forconfiguration into the primary and redundant registers 210-211,respectively. The exclusive-OR logic 212 generates the output FB3 thatis a logical exclusive-OR result of the contents of the registers210-211. Since all of the redundant fuse banks are unblown (i.e., logiclow states), the output FB3 value is simply that which was programmedinto the first fuse banks PFB1-PFBN subsequent to fabrication.

Consider now, though, that design or business requirements dictate thatsome of the information that was programmed into the first fuse banksPFB1-PFBN needs to change. Accordingly, a programming operation isperformed to blow corresponding fuses 203 within the redundant fusebanks RFB1-RFBN in order to change the information that is read atpower-up. By blowing a fuse 203 in a selected redundant bank RFB1-RFBN,the value of a corresponding fuse 203 in the primary fuse bank PFB1-PFBNis logically complemented.

The mechanism of FIG. 2 may be employed to provide for “reblow” of fuses203 within a device 101, but as one skilled in the art will appreciate,a given fuse 203 may only be reblown one time as there is only one setof redundant fuse banks RFB1-RFBN. To provide for additional reblows, acorresponding number of additional fuse banks 202 and registers 210-211must be added to the part 101.

Heretofore, the fuse array mechanisms as discussed above with referenceto FIGS. 1-2 has provided enough flexibility to sufficiently configuremicroprocessor cores and other related devices, while also allowing fora limited number of reblows. This is primarily due to the fact thatformer fabrication technologies, say 65 nanometer and 45 nanometerprocesses, allow ample real estate on a die for the implementation ofenough fuses to provide for configuration of a core 101 disposed on thedie. However, the present inventors have observed that present daytechniques are limited going forward due to two significant factors.First, the trend in the art is to dispose multiple device cores 101 on asingle die to increase processing performance. These so-calledmulti-core devices may include, say, 2-16 individual cores 101, each ofwhich must be configured with fuse data upon power-up/reset.Accordingly, for a 4-core device, four fuse arrays 201 are required inthat some of the data associated with individual cores may vary (e.g.,cache correction data, redundant fuse data, etc.). Secondly, as oneskilled in the art will appreciate, as fabrication process technologiesshrink to, say, 32 nanometers, while transistor size shrinksaccordingly, fuse size increases, thus requiring more die real estate toimplement the same size fuse array on a 32-nanometer die opposed to thaton a 45-nanometer die.

Both of the above limitations, and others, pose significant challengesto device designers, and more specifically to multi-core devicedesigners, and the present inventors note that significant improvementsover conventional device configuration mechanisms can be implemented inaccordance with the present invention, which allows for programming ofindividual cores in a multi-core device along with substantial increasesin cache correction and fuse reprogramming (“reblow”) elements. Thepresent invention will now be discussed with reference to FIGS. 3-12.

Turning to FIG. 3, a block diagram is presented featuring a system 300according to the present invention that provides for compression anddecompression of configuration/repair data for a multi-core device. Themulti-core device comprises a plurality of cores 332 disposed on a die330. For illustrative purposes, four cores 332 CORE 1-CORE 4 aredepicted on the die 330, although the present invention contemplatesvarious numbers of cores 332 disposed on the die 330. In one embodiment,all the cores 332 share a single cache memory 334 that is also disposedon the die 330. A single programmable fuse array 336 is also disposed onthe die 330 and each of the cores 332 are configured to access the fusearray 336 to retrieve and decompress configuration data as describedabove during power-up/reset.

In one embodiment, the cores 332 comprise microprocessor coresconfigured as a multi-core microprocessor 330. In another embodiment,the multi-core microprocessor 330 is configured as an x86-compatiblemulti-core microprocessor. In yet another embodiment, the cache 334comprises a level 2 (L2) cache 334 associated with the microprocessorcores 332. In one embodiment, the fuse array 336 comprises 8192 (8K)individual fuses (not shown), although other numbers of fuses arecontemplated. In a single-core embodiment, only one core 332 is disposedon the die 330 and the core 332 is coupled to the cache 334 and physicalfuse array 336. The present inventors note that although features andfunctions of the present invention will henceforth be discussed in thecontext of a multi-core device 330, these features and functions areequally applicable to a single-core embodiment as well.

The system 300 also includes a device programmer 310 that includes acompressor 320 that is coupled to a virtual fuse array 303. In oneembodiment, the device programmer 310 may comprise a CPU (not shown)that is configured to process configuration data and to program the fusearray 336 following fabrication of the die 330 according to well knownprogramming techniques. The CPU may be integrated into a wafer testapparatus that is employed to test the device die 330 followingfabrication. In one embodiment, the compressor 320 may comprise anapplication program that executes on the device programmer 310 and thevirtual fuse array 303 may comprise locations within a memory that isaccessed by the compressor 320. The virtual fuse array 303 includes aplurality of virtual fuse banks 301, that each comprise a plurality ofvirtual fuses 302. In one embodiment the virtually fuse array 303comprises 128 virtual fuse banks 301 that each comprise 64 virtual fuses302, resulting in a virtual array 303 that is 8 Kb in size.

Operationally, configuration information for the device 330 is enteredinto the virtual fuse array 303 as part of the fabrication process, andas is described above with reference to FIG. 1. Accordingly, theconfiguration information comprises control circuits configuration data,initialization data for microcode registers, microcode patch data, andcache correction data. Further, as described above, the distributions ofvalues for associated with each of the data types is substantiallydifferent from type to type. The virtual fuse array 303 is a logicalrepresentation of a fuse array (not shown) that comprises configurationinformation for each of the microprocessor cores 332 on the die 330 andcorrection data for each of the caches 334 on the die 330.

After the information is entered into the virtual fuse array 303, thecompressor 320 reads the state of the virtual fuses 302 in each of thevirtual fuse banks 301 and compresses the information using distinctcompression algorithms corresponding to each of the data types to rendercompressed fuse array data 303. In one embodiment, system data forcontrol circuits is not compressed, but rather is transferred withoutcompression. To compress microcode register data, a microcode registerdata compression algorithm is employed that is effective for compressingdata having a state distribution that corresponds to the microcoderegister data. To compress microcode patch data, a microcode patch datacompression algorithm is employed that is effective for compressing datahaving a state distribution that corresponds to the microcode patchdata. To compress cache correction data, a cache correction datacompression algorithm is employed that is effective for compressing datahaving a state distribution that corresponds to the cache correctiondata.

The device programmer 310 then programs the uncompressed and compressedfuse array data into the physical fuse array 336 on the die 330.

Upon power-up/reset, each of the cores 332 may access the physical fusearray 336 to retrieve the uncompressed and compressed fuse array data,and reset circuits/microcode (not shown) disposed within each of thecores 332 distributes the uncompressed fuse array data, and decompressesthe compressed fuse array data according to distinct decompressionalgorithms corresponding to each of the data types noted above to rendervalues originally entered into the virtual fuse array 303. The resetcircuits/microcode then enter the configuration information into controlcircuits (not shown), microcode registers (not shown), patch elements(not shown), and cache correction elements (not shown).

Advantageously, the fuse array compression system 300 according to thepresent invention enables device designers to employ substantially fewernumbers of fuses in a physical fuse array 336 over that which hasheretofore been provided, and to utilize the compressed informationprogrammed therein to configure a multi-core device 330 duringpower-up/reset.

Turning now to FIG. 4, a block diagram 400 is presented showing a fusedecompression mechanism according to the present invention. Thedecompression mechanism may be disposed within each of themicroprocessor cores 332 of FIG. 3. For purposes of clearly teaching thepresent invention, only one core 420 is depicted in FIG. 4 and each ofthe cores 332 disposed on the die comprise substantially equivalentelements as the core 420 shown. A physical fuse array 401 disposed onthe die as described above is coupled to the core 420. The physical fusearray 401 comprises compressed microcode patch fuses 403, compressedregister fuses 404, compressed cache correction fuses 405, andcompressed fuse correction fuses 406. The physical fuse array 401 mayalso comprise uncompressed configuration data (not shown) such as systemconfiguration data as discussed above and/or block error checking andcorrection (ECC) codes (not shown). The inclusion of ECC featuresaccording to the present invention will be discussed in further detailbelow.

The microprocessor core 420 comprises a reset controller 417 thatreceives a reset signal RESET which is asserted upon power-up of thecore 420 and in response to events that cause the core 420 to initiate areset sequence of steps. The reset controller 417 includes adecompressor 421. The decompressor 421 has a patch fuses element 408, aregister fuses element 409, and a cache fuses element 410. Thedecompressor also comprises a fuse correction element 411 that iscoupled to the patch fuses element 408, the register fuses element 409,and the cache fuses element 410 via bus 412. The patch fusesdecompressor is coupled to microcode patch elements 414 in the core 420.The register fuses element 409 is coupled to microcode registers 415 inthe core 420. And the cache fuses element 410 is coupled to cachecorrection elements 416 in the core 420. In one embodiment, the cachecorrection elements 416 are disposed within an on-die L2 cache (notshown) that is shared by all the cores 420, such as the cache 334 ofFIG. 3. Another embodiment contemplates cache correction elements 416disposed within an L1 cache (not shown) within the core 420. A furtherembodiment considers cache correction elements 416 disposed to correctboth the L2 and L1 caches described above. Other embodiments contemplatea plurality of on-core caches and a shared cache that is not on-core.

In operation, upon assertion of RESET the reset controller 416 reads thestates of the fuses 402-406 in the physical fuse array 401 anddistributes the states of the compressed system fuses 402 to thedecompressor 421. After the fuse data has been read and distributed, thefuse correction element 411 of the decompressor 421 decompresses thecompressed fuse correction fuses states to render data that indicatesone or more fuse addresses in the physical fuse array 401 whose statesare to be changed from that which was previously programmed. The datamay also include a value for each of the one or more fuse addresses. Theone or more fuse addresses (and optional values) are routed via bus 412to the elements 408-410 so that the states of corresponding fusesprocessed therein are changed prior to decompression of theircorresponding compressed data.

In one embodiment, the patch fuses element 408 comprises microcode thatoperates to decompress the states of the compressed microcode patchfuses 403 according to a microcode patch decompression algorithm thatcorresponds the microcode patch compression algorithm described abovewith reference to FIG. 3. In one embodiment, the register fuses element409 comprises microcode that operates to decompress the states of thecompressed register fuses 404 according to a register fusesdecompression algorithm that corresponds to the register fusescompression algorithm described above with reference to FIG. 3. In oneembodiment, the cache fuses element 410 comprises microcode thatoperates to decompress the states of the compress cache correction fuses405 according to a cache correction fuses decompression algorithm thatcorresponds to the cache correction fuses compression algorithmdescribed above with reference to FIG. 3. After each of the elements408-410 change the states of any fuses whose addresses (and optionalvalues) are provided via bus 412 from the fuse correction element 411,their respective data is decompressed according to the correspondingalgorithm employed. As will be described in further detail below, thepresent invention contemplates multiple “reblows” of any fuse addresswithin the physical fuse array prior to the initiation of thedecompression process executed by any of the decompressors 407-411. Inone embodiment bus 412 may comprise conventional microcode programmingmechanisms that are employed to transfer data between respectiveroutines therein. The present invention further contemplates acomprehensive decompressor 421 having capabilities to recognize anddecompress configuration data based upon its specific type. Accordingly,the recited elements 408-411 within the decompressor 421 are presentedin order to teach relevant aspects of the present invention, however,contemplated implementations of the present invention may notnecessarily include distinct elements 408-411, but rather acomprehensive decompressor 421 that provides functionality correspondingto each of the elements 408-411 discussed above.

In one embodiment, the reset controller 417 initiates execution ofmicrocode within the patch fuses element 408 to decompress the states ofthe compressed microcode patch fuses 403. The reset controller 417 alsoinitiates execution of microcode within the register fuses element 409to decompress the states of the compressed register fuses 404. And thereset controller 417 further initiates execution of microcode within thecache fuses element 410 to decompress the states of the compressed cachecorrection fuses 406. The microcode within the decompressor 421 alsooperates to change the states of any fuses addressed by fuse correctiondata provided by the compressed fuse correction fuses 406 prior todecompression of the compressed data.

The reset controller 417, decompressor 421, and elements 408-411 thereinaccording to the present invention are configured to perform thefunctions and operations as discussed above. The reset controller 417,decompressor 421, and elements 408-411 therein may comprise logic,circuits, devices, or microcode, or a combination of logic, circuits,devices, or microcode, or equivalent elements that are employed toexecute the functions and operations according to the present inventionas noted. The elements employed to accomplish these operations andfunctions within the reset controller 417, decompressor 421, andelements 408-411 therein may be shared with other circuits, microcode,etc., that are employed to perform other functions and/or operationswithin the reset controller 417, decompressor 421, and elements 408-411therein or with other elements within the core 420.

After the states of the fuses 403-406 within the physical fuse array 401have been changed and decompressed, the states of the decompressed“virtual” fuses are then routed, as appropriate to the microcode patchelements 414, the microcode registers 415, and the cache correctionelements 416. Accordingly, the core 420 is configured for operationfollowing completion of a reset sequence.

The present inventors note that the decompression functions discussedabove need not necessarily be performed in a particular order during areset sequence. For example, microcode patches may be decompressedfollowing decompression of microcode registers initialization data.Likewise, the decompression functions may be performed in parallel or inan order suitable to satisfy design constraints.

Furthermore, the present inventors note that the implementations of theelements 408-411 need not necessarily be implemented in microcode versushardware circuits, since in a typical microprocessor core 420 thereexist elements of the core 420 which can more easily be initialized viahardware (such as a scan chain associated with a cache) as opposed todirect writes by microcode. Such implementation details are left up todesigner judgment. However, the present inventors submit that the priorart teaches that cache correction fuses are conventionally read andentered into a cache correction scan chain by hardware circuits duringreset prior to initiating the execution of microcode, and it is afeature of the present invention to implement the cache fusesdecompressor 410 in microcode as opposed to hardware control circuitssince a core's caches are generally not turned on until microcode runs.By utilizing microcode to implement the cache fuses element 410, a moreflexible and advantageous mechanisms is provided for entering cachecorrection data into a scan chain, and significant hardware is saved.

Now referring to FIG. 5, a block diagram is presented illustrating anexemplary format 500 for compressed configuration data 500 according tothe present invention. The compressed configuration data 500 iscompressed by the compressor 320 of FIG. 3 from data residing in thevirtual fuse array 303 and is programmed (i.e., “blown”) into thephysical fuse array 336 of the multi-core device 330. During a resetsequence, as is described above, the compressed configuration data 500is retrieved from the physical fuse array 336 by each of the cores 332and is decompressed and corrected by the elements 408-411 of thedecompressor 421 within each of the cores 420. The decompressed andcorrected configuration data is then provided to the various elements413-416 within the core 420 to initialize the core 420 for operation.

The compressed configuration data 500 comprises one or more compresseddata fields 502 for each of the configuration data types discussed aboveand are demarcated by end-of-type fields 503. Programming events (i.e.,“blows”) are demarcated by an end-of-blow field 504. The compressed datafields 502 associated with each of the data types are encoded accordingto a compression algorithm that is optimized to minimize the number ofbits (i.e., fuses) that are required to store the particular bitpatterns associated with each of the data types. The number of fuses inthe physical fuse array 336 that make up each of compressed data fields502 is a function of the compression algorithm that is employed for aparticular data type. For example, consider a core that comprisessixty-four 64-bit microcode registers which must be initialized to, say,all ones or all zeros. An optimum compression algorithm may be employedto yield 64 compressed data fields 502 for that data type, where each ofthe compressed data fields 502 comprises initialization data for aparticular microcode register where the compressed data fields 502 areprescribed in register number order (i.e., 1-64). And each of thecompressed data fields 502 comprises a single fuse which is blown if acorresponding microcode register is initialized to all ones, and whichis not blown if the corresponding microcode register is initialized toall zeros.

The elements 408-410 of the decompressor 421 in the core 420 areconfigured to utilize the end-of-type fields 503 to determine wheretheir respective compressed data is located within the physical fusearray 336 and the fuse correction decompressor 411 is configured toutilize the end-of-blow fields 504 to locate compressed fuse correctiondata that has been programmed (i.e., blown) subsequent to an initialprogramming event. It is a feature of the present invention to provide asubstantial amount of spare fuses in the physical fuse array 336 toallow for a significant number of subsequent programming events, as willbe discussed in more detail below.

The exemplary compressed type format discussed above is presented toclearly teach aspects of the present invention that are associated withcompression and decompression of configuration data. However, the mannerin which specific type data is compressed, demarcated, and the numberand types of data to be compressed within the fuse array 401 is notintended to be restricted to the example of FIG. 5. Other numbers,types, and formats are contemplated that allow for tailoring of thepresent invention to various devices and architectures extant in theart.

Turning now to FIG. 6, a block diagram is presented illustrating anexemplary format for decompressed microcode patch configuration data 600according to the present invention. During a reset sequence, compressedmicrocode patch configuration data is read by each core 420 from thephysical fuse array 401. The compressed microcode patch configurationdata is then corrected according to fuse correction data provided viabus 412. Then, the corrected compressed microcode patch configurationdata is decompressed by the patch fuses decompressor 408. The result ofthe decompression process is the decompressed microcode patchconfiguration data 600. The data 600 comprises a plurality ofdecompressed data blocks 604 corresponding to the number of microcodepatch elements 414 within the core 420 that require initialization data.Each decompressed data block 604 comprises a core address field 601, amicrocode ROM address field 602, and a microcode patch data field 603.The sizes of the fields 601-603 are a function of the core architecture.As part of the decompression process, the patch fuses decompressor 408creates a complete image of the target data required to initialize themicrocode patch elements 414. Following decompression of the microcodepatch configuration data 600, conventional distribution mechanisms maybe employed to distribute the data 603 to respectively addressed coreand microcode ROM substitution circuits/registers in the microcode patchelements 414.

Now turning to FIG. 7, a block diagram is presented depicting anexemplary format for decompressed microcode register configuration data700 according to the present invention. During a reset sequence,compressed microcode register configuration data is read by each core420 from the physical fuse array 401. The compressed microcode registerconfiguration data is then corrected according to fuse correction dataprovided via bus 412. Then, the corrected compressed microcode registerconfiguration data is decompressed by the register fuses decompressor407. The result of the decompression process is the decompressedmicrocode register configuration data 700. The data 700 comprises aplurality of decompressed data blocks 704 corresponding to the number ofmicrocode registers 415 within the core 420 that require initializationdata. Each decompressed data block 704 comprises a core address field701, a microcode register address field 702, and a microcode registerdata field 703. The sizes of the fields 701-703 are a function of thecore architecture. As part of the decompression process, the registerfuses decompressor 407 creates a complete image of the target datarequired to initialize the microcode registers 415. Followingdecompression of the microcode register configuration data 700,conventional distribution mechanisms may be employed to distribute thedata 703 to respectively addressed core and microcode registers 415.

Referring now to FIG. 8, a block diagram is presented featuring anexemplary format for decompressed cache correction data 800 according tothe present invention. During a reset sequence, compressed cachecorrection data is read by each core 420 from the physical fuse array401. The compressed cache correction data is then corrected according tofuse correction data provided via bus 412. Then, the correctedcompressed cache correction data is decompressed by the cache fusesdecompressor 410. The result of the decompression process is thedecompressed cache correction data 800. Various cache mechanisms may beemployed in the multi-core processor 330 and the decompressed cachecorrection data 800 is presented in the context of a shared L2 cache334, where all of the cores 332 may access a single cache 334, utilizingshared areas. Accordingly, the exemplary format is provided according tothe noted architecture. The data 800 comprises a plurality ofdecompressed data blocks 804 corresponding to the number of cachecorrection elements 416 within the core 420 that require correctivedata. Each decompressed data block 804 a sub-unit column address field802 and a replacement column address field 803. As one skilled in theart will appreciate, memory caches are fabricated with redundant columns(or rows) in sub-units of the caches to allow for a functional redundantcolumn (or row) in a particular sub-unit to be substituted for anon-functional column (or row). Thus, the decompressed cache correctiondata 800 allows for substitution of functional columns (as shown in FIG.8) for non-functional columns. In addition, as one skilled in the artwill concur, conventional fuse array mechanisms associated with cachecorrection include fuses associated with each sub-unit column that areblown when substitution is required by redundant sub-unit columns.Accordingly, because such a large number of fuses are required (toaddress all sub-units and columns therein), only a portion of thesub-units are typically covered, and then the resulting conventionalcache correction fuses are very sparsely blown. And the presentinventors note that it is a feature of the present invention to addressand compress sub-unit column addresses and replacement column addressesonly for those sub-unit columns that require replacement, thusminimizing the number of fuses that are required to implement cachecorrection data. Consequently, the present invention, as limited byphysical fuse array size and the amount of additional configuration datathat is programmed therein, provides the potential for expanding thenumber of sub-unit columns (or rows) in a cache 334 that can becorrected over that which has heretofore been provided. In theembodiment shown in FIG. 8, it is noted that the associated cores 332are configured such that only one of the cores 334 sharing the L2 cache334 would access and provide the corrective data 802-803 to itsrespective cache correction elements 416. The sizes of the fields802-803 are a function of the core architecture. As part of thedecompression process, the cache correction fuses decompressor 410creates a complete image of the target data required to initialize thecache correction elements 416. Following decompression of the cachecorrection data 800, conventional distribution mechanisms in theresponsible core 420 may be employed to distribute the data 802-803 torespectively addressed cache correction elements 416.

Turning to FIG. 9, a block diagram is presented featuring an alternativeexemplary format for decompressed cache correction data 900 according tothe present invention. The embodiment of FIG. 9 may be employed in amulti-core processor configuration such as that of FIG. 4, where each ofthe cores 420 comprise one or more on-core caches (not shown) including,but not limited to, a level one (L1) data cache and an L1 instructioncache. During a reset sequence, compressed cache correction data is readby each core 420 from the physical fuse array 401. The compressed cachecorrection data is then corrected according to fuse correction dataprovided via bus 412. Then, the corrected compressed cache correctiondata is decompressed by the cache fuses decompressor 410. The result ofthe decompression process is the decompressed cache correction data 900.The data 900 comprises a plurality of decompressed data blocks 904corresponding to the number of cache correction elements 416 within thecore 420 that require corrective data. Each decompressed data block 904has a core address field 901, a cache address (CAD) field 905, asub-unit column address field 902, and a replacement column addressfield 903. Thus, the decompressed cache correction data 800 allows forsubstitution of functional columns (or rows) for non-functional columns(or rows) within a cache specified by the CAD field 905, within a core420 specified by the core address field 901. A predefined core addressvalue in the core address field 901 may specify a shared cache, such asan L2 cache, that is not on-core. The sizes of the fields 901-903, 905are a function of the core architecture. As part of the decompressionprocess, the cache correction fuses decompressor 410 creates a completeimage of the target data required to initialize the cache correctionelements 416. Following decompression of the cache correction data 900,conventional distribution mechanisms in the responsible core 420 may beemployed to distribute the data 901-903, 905 to respectively addressedcache correction elements 416.

Turning now to FIG. 10, a block diagram is presented showing anexemplary format for decompressed fuse correction data 1000 according tothe present invention. As has been discussed above, during reset thefuse correction decompressor 411 accesses compressed fuse correctiondata 406 within the physical fuse array 401, decompresses the compressedfuse correction data, and supplies the resulting decompressed fusecorrection data 1000 to the other decompressors 407-410 within the core420. The decompressed fuse correction data comprises one or moreend-of-blow fields 1001 that indicate the end of successivelyprogramming events in the physical fuse array 401. If a subsequentprogramming event has occurred, a reblow field 1002 is programmed toindicate that a following one or more fuse correction fields 1003indicate fuses within the physical fuse array 401 that are to bereblown. Each of the fuse correction fields comprises an address of aspecific fuse within the physical fuse array 401 that is to be reblownalong with a state (i.e., blown or unblown) for the specific fuse. Onlythose fuses that are to be reblown are provided in the fuse correctionblocks fields 1003, and each group of fields 1003 within a given reblowevent is demarcated by an end-of-blow field 1001. If reblow field 1002,properly encoded, is present after a given end-of-blow field 1001, thensubsequent one or more fuse fuses may be configured reblown as indicatedby corresponding fuse correction fields. Thus, the present inventionprovides the capability for a substantial number of reblows for the samefuse, as limited by array size and other data provided therein.

The present inventors have also observed that the real estate and powergains associated with utilization of a shared physical fuse array withinwhich compressed configuration data is stored presents opportunities foradditional features disposed on a multi-core die. In addition, thepresent inventors have noted that, as one skilled in the art willappreciate, present day semiconductor fuse structures often suffer fromseveral shortcomings, one of which is referred to as “growback.”Growback is the reversal of the programming process such that a fusewill, after some time, reconnect after it has been blown, that is, itgoes from a programmed (i.e., blown) state back to an unprogrammed(i.e., unblown) state.

In another aspect, as alluded to above, the present inventors have notedthat there may exist challenges when power gating techniques areemployed to minimize power consumption across a multi-core die, such asthe die 330 of FIG. 3. Such techniques, which are beyond the scope ofthe present application, are employed to detect when one or more cores332 are not being utilized, and in a varying number of ways, the one ormore cores 332 are powered-down (also known as a power gating event).When a power-gated core 332 is required for execution, power is restoredto the core 332 and it begins execution. Of specific interest to thepresent inventors is the case where a core 332 comprises one or moreon-core caches, as is discussed with reference to FIG. 9, where power isremoved from these caches under a power gating event. As one skilled inthe art will appreciate, in order to power up the one or more cachesfollowing the power gating event, the one or more caches must first beconfigured using fuse correction data as is described above. However,one skilled will also appreciate that excessive reading of fuse arraysdecreases the lifetime of the fuses therein. Another issue associatedwith power gating is the excessive time that may be required for eachcore to read cache correction fuses, to decompress compressed fuserepair data, and to configure corrections for each of its respectiveon-core caches. Accordingly, another embodiment of the present inventionis provided to 1) decrease the amount of time required for all cores todecompress and configure their respective on-core caches following apower gating event, and 2) increase the overall lifetime of the fusearray by decreasing the number of accesses by the cores under powergating conditions.

Attention is now directed to FIG. 11, where a block diagram is presenteddetailing a mechanism according to the present invention for rapidlyloading cache correction data into a multi-core device 1100, initiallyand following a power gating event. The device 1100 includes a pluralityof cores 1101 that are configured substantially as described above withreference to FIGS. 3-10. In addition, each of the cores 1101 includesone or more on-core caches CACHE1-CACHEN 1102, a cache repair stores1103, a configuration data stores 1104, reset logic 1105, and sleeplogic 1106. Each of the cores 1102 is coupled to a physical fuse array1110 that is configured as described above with reference to FIGS. 3-10,and to a stores (e.g., random access memory (RAM)) 1130 that is disposedon the same die as the cores 1101, but which is not disposed within anyof the cores 1101. Hence, the stores 1105 is henceforth referred to as“uncore” stores 1105. The uncore stores 1130 includes designatedsub-stores 1131-1134 that each correspond to each of the cores 1101. Themulti-core device 1100 further includes power control 1120 that iscoupled to each of the cores 1101. A sync bus SYNC is coupled to each ofthe cores 1101 to provide for synchronization communications therebetween during power-up, reset, and power gating events.

For purposes of illustration, only four cores 1101, a single physicalfuse array 1110, and a single uncore stores 1130 are shown, however thepresent inventors note that the novel and inventive concepts accordingto the present invention can be extended to a plurality of cores 1101,fuse arrays 1110, and uncore stores 1130 of any number. In oneembodiment, the uncore stores 1130 comprises a random access memory(RAM) that retains power during a power gating event. In one embodiment,the uncore stores 1130 comprises a 4 KB RAM, though other sizes arecontemplated.

In operation, the power control 1120 is configured to perform powergating in order to remove and restore power to one or more of the cores1101. During power-up/reset, the reset logic 1105 on each of the cores1101 is configured to perform, among other operations, configuration ofthe cores 1101 as is described above. In addition, the reset logic 1105is configured to read the configuration data register 1104 to determineif a core 1101 is a master core or a slave core. If the configurationdata indicates that a core 1101 is a slave core, as part of the resetprocess, the slave core waits until the master core signals over thesynchronization bus SYNC that decompressed cache repair data for each ofthe cores 1101 has been read from the fuse array 1110 and has beenwritten into corresponding sub-stores 1131-1134 within the uncore stores1130. Upon indication over SYNC that the corresponding sub-stores1131-1134 have been written, each of the slave cores reads theirrespective decompressed repair data from the corresponding sub-stores1131-1134 and proceeds to configure their respective on-core caches asis described above. If the configuration data indicates that a core 1101is a master core, then as part of power-up/reset, the master core readscache correction data for all of the cores 1101 from the fuse array1110, decompresses the compressed correction data for all of the cores1101, and writes the decompressed cache repair data to the sub-stores1131-1134 corresponding to each of the cores 1101. The master core thensignals to the other cores 1101 over SYNC that writing of thedecompressed cache repair data is completed.

During a power gating event, the power control 1120 removes power fromone or more of the cores 1101 to the extent that power is also removedfrom the core's on-core caches 1102. However, power is not removed fromthe uncore stores 1130, thus preserving the decompressed repair data foreach of the cores 1101. The sleep logic 1106 is configured to determinewhen power is restored to a respective core 1101 following a powergating event, to directly read cache repair data for its on-core cachesfrom its respective sub-stores 1131-1134, and to configure itsrespective repair data stores 1103 for correction of its on-core caches1102, thus drastically reducing the time required to return tooperations following the power gating event, while concurrentlysubstantially increasing the lifetime of the fuse array 1110.

Portions of the present invention and corresponding detailed descriptionare presented in terms of software, or algorithms and symbolicrepresentations of operations on data bits within a computer memory.These descriptions and representations are the ones by which those ofordinary skill in the art effectively convey the substance of their workto others of ordinary skill in the art. An algorithm, as the term isused here, and as it is used generally, is conceived to be aself-consistent sequence of steps leading to a desired result. The stepsare those requiring physical manipulations of physical quantities.Usually, though not necessarily, these quantities take the form ofoptical, electrical, or magnetic signals capable of being stored,transferred, combined, compared, and otherwise manipulated. It hasproven convenient at times, principally for reasons of common usage, torefer to these signals as bits, values, elements, symbols, characters,terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare to be associated with the appropriate physical quantities and aremerely convenient labels applied to these quantities. Unlessspecifically stated otherwise, or as is apparent from the discussion,terms such as “processing” or “computing” or “calculating” or“determining” or “displaying” or the like, refer to the action andprocesses of a computer system, a microprocessor, a central processingunit, or similar electronic computing device, that manipulates andtransforms data represented as physical, electronic quantities withinthe computer system's registers and memories into other data similarlyrepresented as physical quantities within the computer system memoriesor registers or other such information storage, transmission or displaydevices.

Note also that the software implemented aspects of the invention aretypically encoded on some form of program storage medium or implementedover some type of transmission medium. The program storage medium may beelectronic (e.g., read only memory, flash read only memory, electricallyprogrammable read only memory), random access memory magnetic (e.g., afloppy disk or a hard drive) or optical (e.g., a compact disk read onlymemory, or “CD ROM”), and may be read only or random access. Similarly,the transmission medium may be metal traces, twisted wire pairs, coaxialcable, optical fiber, or some other suitable transmission medium knownto the art. The invention is not limited by these aspects of any givenimplementation.

The particular embodiments disclosed above are illustrative only, andthose skilled in the art will appreciate that they can readily use thedisclosed conception and specific embodiments as a basis for designingor modifying other structures for carrying out the same purposes of thepresent invention, and that various changes, substitutions andalterations can be made herein without departing from the scope of theinvention as set forth by the appended claims.

What is claimed is:
 1. An apparatus for providing configuration data toan integrated circuit, the apparatus comprising: a semiconductor fusearray, disposed on a die, into which is programmed compressedconfiguration data for a plurality of cores disposed on said die, andcoupled to said semiconductor fuse array; and a stores, coupled to saidplurality of cores, said stores comprising a plurality of sub-storesthat each correspond to each of said plurality of cores, wherein one ofsaid plurality of cores is configured to access said semiconductor fusearray upon power-up/reset to read and decompress said compressedconfiguration data, and to store a plurality of decompressedconfiguration data sets for one or more cache memories within said eachof said plurality of cores in said plurality of sub-stores, and wherein,following a power gating event, one of said each of said plurality ofcores subsequently accesses a corresponding one of said each of saidplurality of sub-stores to retrieve and employ said decompressedconfiguration data sets to initialize said one or more caches.
 2. Theapparatus as recited in claim 1, wherein a cache fuses decompressorwithin said one of said plurality of cores decompresses said compressedconfiguration data by executing microcode during power-up/reset.
 3. Theapparatus as recited in claim 1, wherein said decompressed configurationdata sets each comprise a first plurality of semiconductor fuses thatindicates one or more sub-unit locations within one of said one or morecache memories that are not to be employed during normal operation. 4.The apparatus as recited in claim 3, wherein said decompressedconfiguration data sets each further comprises a second plurality ofsemiconductor fuses that indicates one or more replacement sub-unitlocations within one of said one or more cache memories that are to beemployed during normal operation in replacement of corresponding ones ofsaid one or more sub-unit locations.
 5. The apparatus as recited inclaim 4, wherein said sub-unit locations and said replacement sub-unitlocations comprise columns and redundant columns, respectively, withinsaid one of said one or more cache memories.
 6. The apparatus as recitedin claim 4, wherein said sub-unit locations and said replacementsub-unit locations comprise rows and redundant rows, respectively,within said one of said one or more cache memories.
 7. The apparatus asrecited in claim 1, wherein the integrated circuit comprises anx86-compatible multi-core microprocessor.
 8. An apparatus for providingconfiguration data to an integrated circuit device, the apparatuscomprising: a multi-core microprocessor, comprising: a semiconductorfuse array, disposed on a die, into which is programmed compressedconfiguration data for a plurality of cores disposed on said die, andcoupled to said semiconductor fuse array; and a stores, coupled to saidplurality of cores, said stores comprising a plurality of sub-storesthat each correspond to each of said plurality of cores, wherein one ofsaid plurality of cores is configured to access said semiconductor fusearray upon power-up/reset to read and decompress said compressedconfiguration data, and to store a plurality of decompressedconfiguration data sets for one or more cache memories within said eachof said plurality of cores in said plurality of sub-stores, and wherein,following a power gating event, one of said each of said plurality ofcores subsequently accesses a corresponding one of said each of saidplurality of sub-stores to retrieve and employ said decompressedconfiguration data sets to initialize said one or more caches.
 9. Theapparatus as recited in claim 8, wherein said cache fuses decompressorwithin said one of said plurality of cores decompresses said compressedconfiguration data by executing microcode during power-up/reset.
 10. Theapparatus as recited in claim 8, wherein said decompressed configurationdata sets each comprise a first plurality of semiconductor fuses thatindicates one or more sub-unit locations within one of said one or morecache memories that are not to be employed during normal operation. 11.The apparatus as recited in claim 10, wherein said decompressedconfiguration data sets each further comprises a second plurality ofsemiconductor fuses that indicates one or more replacement sub-unitlocations within one of said one or more cache memories that are to beemployed during normal operation in replacement of corresponding ones ofsaid one or more sub-unit locations.
 12. The apparatus as recited inclaim 11, wherein said sub-unit locations and said replacement sub-unitlocations comprise columns and redundant columns, respectively, withinsaid one of said one or more cache memories.
 13. The apparatus asrecited in claim 11, wherein said sub-unit locations and saidreplacement sub-unit locations comprise rows and redundant rows,respectively, within said one of said one or more cache memories. 14.The apparatus as recited in claim 8, wherein said multi-coremicroprocessor comprises an x86-compatible multi-core microprocessor.15. A method for configuring an integrated circuit, the methodcomprising: first disposing a semiconductor fuse array on a die, intowhich is programmed compressed configuration data for a plurality ofcores disposed on the die, and coupled to the semiconductor fuse array;and second disposing a stores on the die, the stores comprising aplurality of sub-stores that each correspond to each of the plurality ofcores, wherein one of the plurality of cores is configured to access thesemiconductor fuse array upon power-up/reset to read and decompress thecompressed configuration data, and to store a plurality of decompressedconfiguration data sets for one or more cache memories within the eachof the plurality of cores in the plurality of sub-stores, and wherein,following a power gating event, one of the each of the plurality ofcores subsequently accesses a corresponding one of the each of theplurality of sub-stores to retrieve and employ the decompressedconfiguration data sets to initialize the one or more caches.
 16. Themethod as recited in claim 15, wherein a cache fuses decompressor withinthe one of the plurality of cores decompresses the compressedconfiguration data by executing microcode during power-up/reset.
 17. Themethod as recited in claim 15, wherein the decompressed configurationdata sets each comprise a first plurality of semiconductor fuses thatindicates one or more sub-unit locations within one of the one or morecache memories that are not to be employed during normal operation. 18.The method as recited in claim 17, wherein the decompressedconfiguration data sets each further comprises a second plurality ofsemiconductor fuses that indicates one or more replacement sub-unitlocations within one of the one or more cache memories that are to beemployed during normal operation in replacement of corresponding ones ofthe one or more sub-unit locations.
 19. The method as recited in claim18, wherein the sub-unit locations and the replacement sub-unitlocations comprise columns and redundant columns, respectively, withinthe one of the one or more cache memories.
 20. The method as recited inclaim 18, wherein the sub-unit locations and the replacement sub-unitlocations comprise rows and redundant rows, respectively, within the oneof the one or more cache memories.
 21. The method as recited in claim15, wherein the integrated circuit comprises an x86-compatiblemulti-core microprocessor.